Chiral dynamical aspects of recently measured (low energy) reactions - PowerPoint PPT Presentation

η photoproduction on proton and neutron π 0 η photoproduction Chiral dynamical aspects of recently measured (low energy) reactions at MAMI, ELSA, GRAAL, and other labs M. Döring Helmholtz-Institut für Strahlen- und Kernphysik (HISKP), Universität Bonn Hadron 2011 (München) 13.-17.06.2011 η and π 0 η photoproduction... München, 17.06.2011

η photoproduction on proton and neutron Coupled channels dynamics π 0 η photoproduction Combined Analysis Excess of η n production The reactions γ p → η p and γ n → η n on free and quasi-free nucleons in the deuteron free η p: CBELSA & TAPS, CLAS, LNS quasi-free η N: CBELSA & TAPS (Jaegle et al.) ◮ Some concepts: [Talks of the “Narrow Nuclear Resonances” free η p quasi-free η p 15 conference, Edinburgh 06/2009] quasi-free η n ◮ Non-strange pentaquark, χ QSM prediction [Diakonov et al. ZPhysA 359 (1997), Polyakov et al. ,EPJA 18 10 σ [ µ b] (2003),...] . ◮ Prediction of narrow P11 resonance in π N Arndt et al., PRC 69 ◮ S 11 ( 1650 ) / P 11 ( 1710 ) interference effect 5 [Shklyar, Lenske, Mosel, PLB 650 (2007)] . ◮ Interference of various partial waves 1/2 =1535 MeV s 1/2 =m N +m η [Shyam et al. , arXiv:0808.0632, Choi et al. , PLB 363 (2006)] . s ◮ D 15 ( 1675 ) [ η MAID, NPA 700 (2002)] 0 700 800 900 1000 1100 1200 or P 11 [Fix et al. , EPJA 32 (2007)] ? E γ [MeV] ◮ Around 80 % of σ p is S -wave; and σ n ? ◮ η excess on n found at Graal P -wave? Polarization data [Kuznetsov et al. , PLB 647 (2007)] . [Kuznetsov, Polyakov et al. , APPolonB 39,...(2008)] ◮ Confirmed by CBELSA & TAPS S -wave dominance (?) [Jaegle et al. , PRL 100 (2008)] ; LNS [Miyahara et [Anisovich et al. , EPJA 41 (2009), Miyahara et al. ,PTPS 168 (2007)] . al. ,PTPS 168 (2007)] . η and π 0 η photoproduction... München, 17.06.2011

η photoproduction on proton and neutron Coupled channels dynamics π 0 η photoproduction Combined Analysis Coupled channels and unitarity N. Kaiser et al., PLB 362 (1995) 23, NPA 612 (1997) 297, T. Inoue et al. , PRC 65 (2002) 035204 Nieves, Ruiz Arriola, PRD 64 (2001) García Recio, Lutz, Nieves, PLB 582 (2004) ◮ ( 0 − ) M ⊗ ( 1 / 2 + ) B in SU ( 3 ) : Coupled channels in S = Q = 0 are π N , η N , K Σ , K Λ . ◮ Interaction V from the LO chiral Lagrangian: (Isovector) Weinberg-Tomozawa interaction. ◮ Unitarization through the Bethe-Salpeter equation Loop G T = ( 1 − VG ) − 1 V . “=” ◮ Strong channel coupling. ◮ Attraktion + Unitarization → Pole in the scattering amplitude. Dynamically generated N ∗ ( 1535 ) (not the main issue here). η and π 0 η photoproduction... München, 17.06.2011

η photoproduction on proton and neutron Coupled channels dynamics π 0 η photoproduction Combined Analysis Photon coupling to the coupled channels Formalism along the lines of [Haberzettl, Nakayama, Krewald, PRC 56 (1997), PRC 74 (2006)] ◮ Electromagnetic properties provide independent tests, because the couplings of the photon to the mesons & baryons are well known. Predictions of, e.g., helicity amplitudes [D. Jido, M. D., E. Oset, PRC77 (2008)] . (a) (b) 1. γ p , γ n initial state. 2. Excitation of intermediate meson-baryon states MB ( π N , η N , K Λ , K Σ ). 3. Superposition of initial ( MB ) initial → MB final . 4. MB final = π N , η N , K Λ , K Σ . Details/other results ◮ Global fit to 18 reactions (Multipoles & partial waves): γ N , π N → η N , π N , K Λ ◮ Gauge invariance ensured. η and π 0 η photoproduction... München, 17.06.2011

η photoproduction on proton and neutron Coupled channels dynamics π 0 η photoproduction Combined Analysis η photoproduction on free p and n M. D., K. Nakayama, PLB 683 (2010) 20 K Λ K Σ 15 σ [ µ b] 10 5 0 700 800 900 1000 1100 1200 E γ [MeV] Data: Jlab-Clas, Bonn CB-Elsa, LNS [Recent high precision MAMI data not yet included (PRC 82, 2010)]. Solid: γ p → η p Dotted: γ n → η n η and π 0 η photoproduction... München, 17.06.2011

η photoproduction on proton and neutron Coupled channels dynamics π 0 η photoproduction Combined Analysis η photoproduction on quasi-free p and n Inclusion of Fermi motion in the deuteron in a spectator model. 20 15 σ [ µ b] 10 5 1/2 =1535 MeV s 1/2 =m N +m η s 0 700 800 900 1000 1100 1200 E γ [MeV] Data: I. Jaegle et al. , CBELSA & TAPS Solid/Black: γ p → η p Dotted/Red: γ n → η n η and π 0 η photoproduction... München, 17.06.2011

η photoproduction on proton and neutron Coupled channels dynamics π 0 η photoproduction Combined Analysis The ratio σ n /σ p = σ ( γ n → η n ) σ ( γ p → η p ) ◮ Intermediate states in photon loops, Q = 0 , 1 : ◮ π − p , π 0 n , η n , K 0 Λ , K + Σ − , K 0 Σ 0 2 ◮ π 0 p , π + n , η p , K + Λ , K + Σ 0 , K 0 Σ + 1.5 σ n / σ p 1 0.5 η N K Λ K Σ 1/2 =1535 MeV s 0 700 800 900 1000 1100 1200 E γ [MeV] ◮ Photon excitation of intermediate, SU(3) allowed states (photon loops) renders σ n Data: I. Jaegle et al. , CBELSA & TAPS and σ p differently. K Σ threshold enhancement in σ n . ◮ Solid line: Present result (incl. Fermi) ◮ Peak in σ n /σ p : Direkt consequence of Weinberg-Tomozawa driving term from LO ◮ Dotted: No γ K + Λ χ Lagrangian. ◮ Dash-dotted: from NLO chiral (x20) Further tests of the model ◮ Dashed: no Fermi motion ◮ η and π 0 η photoproduction... München, 17.06.2011

η photoproduction on proton and neutron Coupled channels dynamics π 0 η photoproduction Combined Analysis The ratio σ n /σ p = σ ( γ n → η n ) σ ( γ p → η p ) ◮ Intermediate states in photon loops, Q = 0 , 1 : ◮ π − p , π 0 n , η n , K 0 Λ , K + Σ − , K 0 Σ 0 2 ◮ π 0 p , π + n , η p , K + Λ , K + Σ 0 , K 0 Σ + 1.5 σ n / σ p 1 0.5 η N K Λ K Σ 1/2 =1535 MeV s 0 700 800 900 1000 1100 1200 E γ [MeV] ◮ Photon excitation of intermediate, SU(3) allowed states (photon loops) renders σ n Data: I. Jaegle et al. , CBELSA & TAPS and σ p differently. K Σ threshold enhancement in σ n . ◮ Solid line: Present result (incl. Fermi) ◮ Peak in σ n /σ p : Direkt consequence of Weinberg-Tomozawa driving term from LO ◮ Dotted: No γ K + Λ χ Lagrangian. ◮ Dash-dotted: from NLO chiral (x20) Further tests of the model ◮ Dashed: no Fermi motion ◮ η and π 0 η photoproduction... München, 17.06.2011

η photoproduction on proton and neutron Coupled channels dynamics π 0 η photoproduction Combined Analysis The ratio σ n /σ p = σ ( γ n → η n ) σ ( γ p → η p ) ◮ Intermediate states in photon loops, Q = 0 , 1 : ◮ π − p , π 0 n , η n , K 0 Λ , K + Σ − , K 0 Σ 0 2 ◮ π 0 p , π + n , η p , K + Λ , K + Σ 0 , K 0 Σ + 1.5 σ n / σ p 1 0.5 η N K Λ K Σ 1/2 =1535 MeV s 0 700 800 900 1000 1100 1200 E γ [MeV] ◮ Photon excitation of intermediate, SU(3) allowed states (photon loops) renders σ n Data: I. Jaegle et al. , CBELSA & TAPS and σ p differently. K Σ threshold enhancement in σ n . ◮ Solid line: Present result (incl. Fermi) ◮ Peak in σ n /σ p : Direkt consequence of Weinberg-Tomozawa driving term from LO ◮ Dotted: No γ K + Λ χ Lagrangian. ◮ Dash-dotted: from NLO chiral (x20) Further tests of the model ◮ Dashed: no Fermi motion ◮ η and π 0 η photoproduction... München, 17.06.2011

η photoproduction on proton and neutron Coupled channels dynamics π 0 η photoproduction Combined Analysis The ratio σ n /σ p = σ ( γ n → η n ) σ ( γ p → η p ) ◮ Intermediate states in photon loops, Q = 0 , 1 : ◮ π − p , π 0 n , η n , K 0 Λ , K + Σ − , K 0 Σ 0 2 20x ◮ π 0 p , π + n , η p , K + Λ , K + Σ 0 , K 0 Σ + 1.5 σ n / σ p 1 0.5 η N K Λ K Σ 1/2 =1535 MeV s 0 700 800 900 1000 1100 1200 E γ [MeV] ◮ Photon excitation of intermediate, SU(3) allowed states (photon loops) renders σ n Data: I. Jaegle et al. , CBELSA & TAPS and σ p differently. K Σ threshold enhancement in σ n . ◮ Solid line: Present result (incl. Fermi) ◮ Peak in σ n /σ p : Direkt consequence of Weinberg-Tomozawa driving term from LO ◮ Dotted: No γ K + Λ χ Lagrangian. ◮ Dash-dotted: from NLO chiral (x20) Further tests of the model ◮ Dashed: no Fermi motion ◮ η and π 0 η photoproduction... München, 17.06.2011

η photoproduction on proton and neutron Coupled channels dynamics π 0 η photoproduction Combined Analysis The ratio σ n /σ p = σ ( γ n → η n ) σ ( γ p → η p ) ◮ Intermediate states in photon loops, Q = 0 , 1 : ◮ π − p , π 0 n , η n , K 0 Λ , K + Σ − , K 0 Σ 0 2 ◮ π 0 p , π + n , η p , K + Λ , K + Σ 0 , K 0 Σ + 1.5 σ n / σ p 1 0.5 η N K Λ K Σ 1/2 =1535 MeV s 0 700 800 900 1000 1100 1200 E γ [MeV] ◮ Photon excitation of intermediate, SU(3) allowed states (photon loops) renders σ n Data: I. Jaegle et al. , CBELSA & TAPS and σ p differently. K Σ threshold enhancement in σ n . ◮ Solid line: Present result (incl. Fermi) ◮ Peak in σ n /σ p : Direkt consequence of Weinberg-Tomozawa driving term from LO ◮ Dotted: No γ K + Λ χ Lagrangian. ◮ Dash-dotted: from NLO chiral (x20) Further tests of the model ◮ Dashed: no Fermi motion ◮ η and π 0 η photoproduction... München, 17.06.2011